Answer:
17. The median of trapezoid = 10 units
m<A = 68°
18. ΔABC ≅ ΔADC
Explanation:
17). To find the median of trapezoid
From the figure we can see a trapezoid ABCD.
Median of trapezoid = Half the sum of bases
Here base of trapezoid are 15 and 5 units
Median = (15 + 5)/2 = 10
Also it is given that ABCD is isosceles trapezoid,
Therefore m<A =m < B = 68°
18). To prove ΔABC ≅ ΔADC
From the second figure we can see two triangles ΔABC and ΔADC
It is given that,
<BCA = <ACD
<B = <D = 90°
From figure we can see that, AC is common for both the triangle.
Therefore by HL congruence we can see that, ΔABC ≅ ΔADC